Lecture 2.2

Question 1

Energy sources for imaging can be putin two categories;

Ionising - detach electrons from atoms

e.g…..

Non-ionising

e.g…..

Answer 1

Ionising

x-rays

gamma rays (NM)

positrons (PET) decay - gamma rays

Nonionising

Sound

FM radio/magnetism (MRI)

Question 2

Radiography:

Pros and cons?

Answer 2

Pros:

Cheap

avaialble

excellenet spatial resolution

Cons:

ionising radiation

poor contrast resolution

planar technique

Question 3

True or False

X-rays are used for detection of breast cancer

Answer 3

True

Question 4

True or False:

CT scans use x rays

Answer 4

True

Question 5

CT

pros and cons?

Answer 5

Pros:

Cross-sectional

better contrast resolution than radiography

good spatial resolution

Cons:

more ionising radiaiton

expensive

Question 6

Ultrasound

uses piezoelectric crystal to produce ____waves

sound is ______back to the probe

Answer 6

Ultrasound

uses piezoelectric crystal to produce sound waves

sound is reflected back to the probe

(same idea as sonar

Question 7

pros/cons on Ultrasound?

Answer 7

Pros:

no-ionising radiation

cheaper than CT

freely avaialbe

Cons:

oprator dependent (hands on)

sound penetration: (can’t go well through fat/bone/gas)

Question 8

Uses of Ultrasound:

Answer 8

children

pregnancy

screening for abdominal symptoms

pelviuc pathology

small parts (thyroid, testis, breast)

musculo-skeletal (esp. muscles, tendons, ligaments)

blood vessels (Doppler)

Question 9

MRI

very powerful magnet and radio generator

looking at _____ denisty (most in water)

Answer 9

MRI

very powerful magnet and radio generator

looking at proton denisty (most in water)

Question 10

MRI pros and cons:

Answer 10

Pros:

non-ionising radiation

excellent contrast resolution

reasonalble spatial resolution

Cons:

expensive

strong magnet (issues with metal inside people)

long scan times

claustrophobia

Question 11

Uses of MRI:

Answer 11

brain (except acute trauma)

spine for pain or neurological deficit

joints for pain, bones where X-rays not helpful

liver and biliary tree where Ultrasound not helpful

breast in young female for CA

pelvic malignancy

non-invasive angiography

Question 12

Nuclear medicine:

_____ emitting radioisotopes that are injected

targets specific organs - by attaching to a ___

Answer 12

Nuclear medicine:

gamma emitting radioisotopes that are injected

targets specific organs - by attaching to a drug

Question 13

NM:

you want high signal coming from the ____ and low emmission from the ________ _____

Answer 13

you want high signal coming from the organ and low emmission from the surrounding tissues

Question 14

NM pros and cons:

Answer 14

Pros:

excellent signal to noise

extremely senesitive

Cons:

ionising radiation

very poor spatial resolution

poor specificity ofor apthology

expensive

Question 15

ALARA;

a principle of ionising radiaton

dose shoud be “just” enough to be clinically useful

Answer 15

ALARA;

a principle of ionising radiaton

dose shoud be “just” enough to be _______ useful

Question 16

How do you reduce the harmful effects of ionising radiation?

Answer 16

Fewer procedures

prolonged interval between expsure (allow DNA to repair)

not children/pregnant (rapidly dividing cells)